2 Answers
2

You can use the standard Gnome video player Totem.
From the Totem manual:

3.14. To Create a Screenshot Gallery

To create a gallery of screenshots of the movie or visualization that is playing,
choose Edit ▸ Create Screenshot Gallery. The Save Gallery dialog is displayed. Choose a location and insert the filename as which you want to save the gallery image, then click on the Save button to save the screenshot.

You may specify the width of the individual screenshots in the gallery using the Screenshot width entry. The default width is 128 pixels.
You may also specify the number of screenshots to be put in the gallery. By default, this is calculated based on the length of the movie; however, this may be overridden by deselecting the Calculate the number of screenshots checkbox and entering the new number in the Number of screenshots spin box.